1. Field of the Invention
The present invention relates to a recording head capable of recording high quality images rapidly and reliably, and to an inkjet recording device equipped with the recording head.
2. Description of Related Art
In order to record high-quality images rapidly and reliably using an on-demand inkjet recording device having a plurality of densely integrated nozzles, it is particularly necessary to increase the ink droplet ejection rate and to achieve stable ink ejection at a high frequency.
One structure of nozzles configured of push-type piezoelectric elements is disclosed in Japanese unexamined patent application publication No. HEI-6-270403. In this push-type piezoelectric element system, vertical vibrations of a pole-shaped piezoelectric element push a diaphragm that constitutes one surface of an ink pressure chamber, decreasing the volume in the pressure chamber and causing an ink droplet to be ejected from the nozzle hole. Pole-shaped piezoelectric elements of a number equal to the number of nozzle holes are arranged in a row. One end of the pole-shaped piezoelectric element opposite another side that contacts the diaphragm is fixed to a support base. The support base is affixed to a head housing.
However, when piezoelectric elements are driven in a recording head having this construction, vertical vibrations from the piezoelectric element are transferred not only to the diaphragm, but also to the support base, the head housing, and the like, making ink droplet ejection unstable. Vibrations from the piezoelectric element also affect nozzles adjacent to the nozzle corresponding to the piezoelectric element, generating what is called cross talk, which produces fluctuations in the ink droplet ejection characteristics.
In order to avoid this problem, Japanese unexamined patent application publication No. 2002-361868 discloses an inkjet recording device in which the piezoelectric element support base is configured of a stiff member capable of absorbing vibrations from the piezoelectric element.
Another inkjet recording device disclosed in Japanese unexamined patent application publication No. HEI-9-99554 supplies a piezoelectric element with a voltage considering the effects of vibrations on neighboring piezoelectric elements to alleviate mutual interference between nozzle units.
However, when using one of the methods described in Japanese unexamined patent application publications Nos. 2002-361868 and HEI-9-99554, abnormal vibrations were generated in a specific frequency range in parts or all of the print head when ejecting ink droplets. These abnormal vibrations generate ink mist or cause the ink ejection direction to deviate from the desired direction. These abnormal vibrations also cause ink to protrude from the nozzle hole and wet the region around the hole. This can result in ejection failures or, when ink droplets are ejected, irregular ejection characteristics due to cross talk.
This is particularly problematic when lengthening the head to integrate a plurality of nozzles therein, as in a push-type on-demand recording head, or when lowering the resonance frequency of such components as the piezoelectric element support base and increasing the excitation force in order to eject ink with a high viscosity.
Further, conventional recording head driving devices are provided with control elements, such as switching elements, and a flexible cable connecting each control element to a piezoelectric element, in order to selectively apply a drive pulse to piezoelectric elements corresponding to each nozzle. Accordingly, a recording head having a plurality of densely integrated nozzles requires a larger number of control elements and wires in the flexible cable, thereby increasing costs and leading to problems in mounting.